Grade 2 students have been studying about matter within their current unit of inquiry (UOI): How the World Works.  The theme of the inquiry is Matter interacts in a variety of ways 物質は様々な相互作用を持つ。  To help students understand that air is matter and takes up space, students tried to blow balloons up inside of PET bottles.  At first, no one was able to do so, but then the class experimented with created a hole in the bottle to allow the air to escape when the balloon was blown up.  Students were amazed that they were also able to keep the balloon inflated by covering the hole with their finger.